Active transport

• Active Transport


  Process where substances need to be absorbed against a concentration gradient, ie from a lower to a higher concentration
• Root Hair Cell


  • Cells on plant roots that grow into "hairs" which stick out into the soil
  • Each branch of a root will be covered in millions of these microscopic hairs
  • Gives the plant a large surface area for absorbing water and mineral ions from the soil
• Plants need mineral ions for healthy growth
• The concentration of minerals is usually higher in the root hair cells than in the soil around them
• Root hair cells can't use diffusion to take up minerals from the soil
• Root Hairs Take in Minerals Using Active Transport

  1. Minerals should move out of the root hairs if they followed the rules of diffusion

  2. Active transport allows the plant to absorb minerals from a very dilute solution, against a concentration gradient

  3. Active transport needs energy from respiration to make it work
• Active transport also happens in humans, for example in taking nutrients from the gut and from the kidney tubules
• We Need Active Transport to Stop Us Starving

  1. When there's a lower concentration of nutrients in the gut than there is in the blood, active transport allows nutrients to be taken into the blood, despite the fact that the concentration gradient is the wrong way

  2. Active transport uses energy
• Concentration of glucose and amino acids in the gut is higher than in the blood


  They diffuse naturally into the blood
• Concentration of nutrients in the gut is lower than in the blood


  Active transport is used to take them into the blood
• Glucose can be taken into the bloodstream when its concentration in the blood is already higher than in the gut, and then transported to cells for respiration